Temporal trends in the foliar nutritional status of the French, Walloon and Luxembourg broad-leaved plots of forest monitoring

Abstract

Abstract• Two decades after the launching of the monitoring program of forest ecosystems in Europe (ICP forests), a unique data set is now available regarding the foliar nutritional status of the main broadleaved species growing in much-diversified sites (soil, climate).• This study focuses on the foliar concentration time series (1993 to 2005) of the French (RENECO-FOR), Walloon and Luxemburg broad-leaved plots. The aim is to show long-term trends while taking the inter-plot and inter-annual variability into account.• Two kinds of statistical processing were used to analyze the data on foliar chemistry: principal component analysis (PCAs) and linear mixed models. In general, the main temporal trends reveal a decrease in the foliar P concentration and a decrease in the foliar Ca concentration, except for European beech on acid soils.• These temporal patterns confirm the trends previously observed and could be explained by the joint actions of several processes that influence tree nutrition in the long term: tree age, N and S deposition, harvesting and climate. Mots-clés :Quercus robur / Quercus petraea / Fagus sylvatica / analyse de tendance / phosphore Résumé -Évolution du statut nutritionnel foliaire des placettes de feuillus des réseaux français, wallon et luxembourgeois de suivi des forêts.• Deux décennies après le lancement du programme de suivi des écosystèmes forestiers en Europe (ICP forests), un jeu de données unique est à présent disponible concernant le statut nutritionnel foliaire des principales essences feuillues implantées dans des stations très diversifies du point de vue du sol et du climat.• Cette étude se focalise sur les séries chronologiques de teneurs foliaires (1993 à 2005) des placettes de feuillus de France, Wallonie et Luxembourg. L'objectif est de mettre en évidence la tendance à long-terme tout en prenant en compte la variabilité inter-placette et inter-annuelle.• Deux types de traitements statistiques ont été utilisés pour analyser les données de nutrition foliaire : l'analyse en composantes principales (ACP) et les modèles linéaires mixtes. Globalement, la tendance principale est une diminution généralisée de la teneur foliaire en P and une diminution de la teneur foliaire en Ca, sauf en ce qui concerne le hêtre sur sols acides.• Ces tendances temporelles confirment celles déjà observées par le passé et pourraient être expliquées par l'action combinée de différents processus influençant la nutrition des arbres à long-terme (vieillissement, dépôts azotés et soufrés, exploitation, fructification).

Phosphorus nutrition of beech (Fagus sylvatica L.) is decreasing in Europe

“…This is in accordance with the findings of some earlier national case studies carried out in Western and Central Europe (Braun et al 2010;Jonard et al 2009). Even though plots in Eastern Europe are underrepresented in this study, it can be stated that foliar P concentrations decreased also in these countries ( Fig.…”

“…For example, autumnal withdrawal of P is significantly reduced at high N deposition levels (Braun and Flückiger 2013). Furthermore, increased fructification is P demanding and may deplete P reserves in trees (Jonard et al 2009;Khanna et al 2009). Last decennia, masting of beech occurred at shorter intervals in Europe, and masting events were found to be linked to climate parameters (Övergaard et al 2007;Piovesan and Adams 2001).…”

“…Reduced forest growth might be the consequence of reduced leaf size and total leaf area, which was found to be the response to low P supply in white birch (Danyagari and Dang 2014). P deficiencies, decreasing foliar P levels, or high N/P ratios have been reported for beech forests in Switzerland (Braun et al 2010), France, Belgium, and Luxemburg (Jonard et al 2009). However, many questions concerning forest P nutrition are still unexplained.…”

Sources of variability in tissue chemistry in northern hardwood species

“…Examples of reported changes in foliar chemistry include increases in nitrogen concentration and decreases in phosphorus, calcium, magnesium, and potassium concentrations in Europe from 1969 to 1997 (Duquesnay et al 2000), from 1984 to 1995 (Flückiger and Braun 1998), and from 1993 to 2005 (Jonard et al 2009). However, there are many sources of uncertainty in estimating long-term changes in tree nutrients, some of which are not commonly accounted for.…”

Morphology and foliar chemistry of containerized Abies fraseri (Pursh) Poir. seedlings as affected by water availability and nutrition

“…The marginal effect of irrigation and lack of interaction between foliar N and P and irrigation may have been caused by the high rate of leaching observed in high irrigation treatments. The response to the addition of water and nutrients can be variable and depends on seasonal site water balance and initial soil fertility (Jonard et al, 2009;Trichet et al, 2008). Therefore, increased water addition through irrigation is likely to lead to soil saturation and cause a flow-through of highly mobile nutrients present in the soil solution such as nitrates below the root zone.…”